Sim Van der Ryn has been a leader in sustainable architecture for over 40 years. As well as creating a portfolio of inspiring green designs -- notably the 1977 Bateson Building in Sacramento -- he is also a teacher and an author. His most recent book "Design for Life" traces his ancestral and ecological design roots. Principal Voices talked to Van der Ryn about the passion which continues to consume his life.

It is being billed as the ultimate book about the world and it is something of a landmark in its own right. "Earth" -- the biggest atlas ever to be published -- promises to be a luxurious benchmark in cartography.

Of all the power supplies in the energy mix, nuclear has historically been the most criticized and controversial. But this most unpopular of power sources has recently resurfaced in political and economic dialogue.

David Crane is a man who isn't afraid of a challenge. When he took the helm at NRG Energy in the winter of 2003, the company was mired in Chapter 11 bankruptcy proceedings -- just one of many companies caught in the meltdown of the U.S. power generation industry, instigated by the scandalous collapse of Texan power giant Enron in 2001.

Later this summer, a motor rally will make its way across Europe. Nothing strange in that you might think. But this is a race with a difference -- a "banger rally" if you like -- and one with a well-tuned environmental message.

As a product designer, Agustin Otegui's has to "think big" about the objects he creates. From novel portable chairs made out of shovels to chrome radiators that look like modern works of art, he recasts the mundane in a modernist and functional new light.

Whilst the energy grids we rely on to provide us with cheap and reliable electricity may have been fit for purpose in the 20th century, it is now abundantly clear that the design of 21st century energy networks will have to be very different. In Europe, the foundations for a secure, flexible and more energy efficient future are already being laid.

Oxfam's new book "From Poverty to Power: How Active Citizens and Effective States Can Change the World" is a detailed and vivid account of poverty, its effects and how it can be eradicated. Principal Voices spoke to the book's author and Head of Research at Oxfam GB, Duncan Green about the charity's prescription for change.

Forget the "Bird's Nest" and the "Water Cube". If you're traveling to China this summer, or even if you are watching the Olympics on television, make sure you look out for a glittering new landmark structure in Beijing.

Co-founder and executive director of Architecture for Humanity, Cameron Sinclair opened the second Principal Voices debate on Design for Good by outlining just what the term means to him, but also what it means to the communities his design solutions are aimed at.

You might want to go green, but how do you know what you're buying is truly ethical? Greenwash -- the ignoble art of misleading consumers about a product's true green worth -- is on the rise. But thanks to the work of increasingly vigilant regulators, some of the more curious and downright spurious claims are being weeded out.

The site has been secured, the tents pitched, banners raised and, most importantly, compost loos installed; there is little to do now but wait for thousands of campers to arrive for one of Britain's biggest environmental protests this year.

Imagine every time you closed your curtains, you were capturing enough solar energy to power your laptop. The technology is available, but no one's packaged it up in a handy DIY kit at your local hardware store.

Imagine if cars ran on household waste, if gas tanks were filled with ethanol made from wood chips. Well, the technology to make it happen is already a reality and companies are now racing to bring this kind of fuel to a gas pump near you.

If you've ever found yourself in your local supermarket agonizing about whether the organic apples will be a more nutritional and greener choice than the cheaper non-organic ones, you're probably not alone.

Twenty four hours before the greatest scientific experiment of our time gets underway at CERN's Large Hadron Collider, political and scientific dignitaries assembled at a site a few hundred miles north east of the French/Swiss border at a site in Germany to inaugurate another groundbreaking engineering test.

The creators are billing it as one of the coolest hostels in the world and it's undoubtedly one of the most novel overnight stays you are ever likely to experience. Welcome to the Jumbo Hostel -- an old Boeing 747 which is being converted into a 25-room hostel at the Stockholm-Arlanda airport.

It can often seem like hard work keeping track of the changes happening to our planet. Another day, another new prediction. Another week, another warning. It's enough to make even the most conscientious climate change student issue a weary discombobulated sigh.

You might have thought that recycling is limited to paper, plastics and glass. Well, think again. A Californian company is developing a new technique for recycling carbon dioxide, or CO2, and turning it back into fuel.

Juliet Davenport is the Oxford University-educated chief executive and founder of Good Energy, a 100 percent renewable electricity supplier in the UK. When she participated in the Principal Voices project in 2007, she talked about the need to embrace renewable energy.

Micro wind turbines are beginning to pop up all over our urban and rural landscapes. But is it worth investing your hard-earned cash in your very own wind machine? In short, it depends. Take a look at our quick guide to see if "small wind" could help you reduce your energy bills and your carbon footprint.

For a century the gasoline engine has remained largely unchallenged, seeing off all pretenders to its crown. But with concerns about greenhouse gas emissions and a host of new contenders looming large in the rear view mirror, is the gasoline-fueled automobile due to be overtaken by a fleet of cleaner, leaner rivals?

In the stylishly minimal surroundings of Singapore's Red Dot design museum, architect and innovative-thinker Cameron Sinclair opened the second Principal Voices debate of 2008 with a clear statement: "There is a lot of 'design for bad' out there."

From columns of cloud streaking over the Caspian Sea in January to vast tracts of cleared forest in Bolivia in December. In 2008, the NASA Earth Observatory has captured more stunning images of the Earth.

The United Nations Climate Conference underway in Poznan, Poland, hopes to build on the Bali Action Plan adopted by over 180 countries in 2007 and lay the groundwork for a new global climate agreement scheduled to be ratified at next year's climate summit in Denmark.

There's no point in having a debate without varied points of view. Send us an email by filling out the form on the front page, file an iReport or click on the "Sound Off" button at the bottom of this page.

If ever there were a person born to be a champion of the environment, it's Alexandra Cousteau. Her father is the enigmatic environmentalist Philippe Cousteau and her grandfather is legendary French explorer Jacques-Yves Cousteau.

It is an unusual art auction where making money isn't a great concern. But that is the case this weekend when a series of paintings go on the block with the purpose of drawing attention to climate change.

Dr Jan Zalasiewicz is the author of "The Earth After Us -- What legacy will humans leave in the rocks?" His book examines what might remain of our civilization in the strata 100 million years from now, and how aliens might piece together the story of the planet and our brief but dramatic impact on it.

One look outside the window gives a glimpse of the "economics of energy" in Doha, Qatar. Cranes dot the tops of half-finished towers, a monumental work in progress; the result of vast energy wealth being pumped out of the ground and poured into project after project.

Governments around the world continue to pump billions of dollars into financial markets, but there is still no telling whether the "injections of liquidity" will be enough to prevent "this sucker" -- to quote the President of the United States -- from going down.

As an organization they're used to investing billions of dollars in scientific experiments that further our knowledge of earth and space. But the only bill to speak of on this occasion is orange and attached to the body of a rubber duck.

Wayne Hemingway is the English designer who made his name with trendy fashion label Red or Dead. Often outspoken, and known for his green values, Hemingway now designs housing projects -- and he's on a mission to change how we think about sustainable housing.

The term "eco community" might conjure up an image of bearded hippies tending an allotment before sharing a mung bean stew. But as today's urbanites become more concerned about reducing their carbon footprints, some are finding that modern eco communities offer them a way to live sustainably without foregoing their home comforts.